1. Field of the Invention
The present invention relates generally to enclosures for in-ground meters for both residential and commercial use. In particular, this invention relates to covers for such meter enclosures that are designed for use under traffic loading conditions, and a method for making those covers.
2. Description of the Prior Art
On-site water meters are commonly used to permit a utility to determine the amount of water usage by a customer. Typically, the water meter is located in a meter enclosure extending into the ground adjacent the customer""s residence or commercial building, to permit easy access by the utility meter-reader. The in-ground meter enclosure may be located in an environment not subject to traffic loading conditions (i.e., where automobiles, trucks and other traffic are not likely to pass across the top of the meter enclosure) or may in fact be exposed to potential traffic loading conditions. In the past, it has been customary for the water utility to maintain two inventories of covers for meter enclosures, one for use in non-traffic conditions and the other for situations where the meter enclosure may be exposed to traffic. Meter enclosure covers for non-traffic use are generally inexpensive, lightweight and not capable of sustaining traffic loads. On the other hand, meter enclosure covers for use in traffic loading conditions are typically made of high-grade steel and are generally substantially more expensive than the first type described previously. But maintaining two different inventories for such meter covers can be quite expensive. Further, while a meter installation may initially be perceived to be in a non-traffic environment, circumstances may change and the meter cover later subjected to traffic loading. In that situation, the meter cover may be broken, creating possible personal injury hazards. Thus, there is a need for a meter enclosure cover which is relatively low in cost, but is capable of withstanding significant traffic loads.
The present invention is directed to an in-ground meter enclosure cover for use in potential traffic loading conditions, and comprises a relatively thin plate member having a pattern of interconnecting rib members extending from the bottom side and including a peripheral rib member. The plate member and the interconnecting and peripheral rib members are dimensioned and fabricated from a suitable material, preferably a ductile iron alloy, such that the composite construction has sufficient structural strength to withstand total loads of at least about 20,000 pounds on the top side of the plate member.
In the preferred embodiment, the plate member and the rib members are cast together as a unitary cover, with unitary cast joints between the intersections of the rib members.
The cover further comprises a meter access opening extending through the plate member between the top and bottom sides and intermediate between adjacent interconnecting rib members, with a meter access lid pivotally positioned in the meter access opening.
Preferably, the cover is elongated in one direction, with the rib members including interior ribs comprising at least two longitudinal ribs extending parallel to the direction of cover elongation and at least three lateral ribs extending generally normal to, and intersecting with, the longitudinal ribs at spaced unitary cast joints. The rib members all have a dimension extending normal from the bottom side which is substantially greater than the dimension of the plate member between the top and bottom sides. By way of example, the peripheral rib has a dimension from the bottom side of the plate member which is on the order of at least six times the thickness of the plate member; similarly, the interior ribs have a dimension extending from the bottom side of the plate member which is on the order of at least four times the thickness of the plate member. Preferably, a portion of one of the elongated ribs is substantially thicker adjacent to and generally parallel with the bottom side of the plate member along the meter access opening, and includes a recess adapted to support the meter access lid when closed.